Future mobile phones are expected to be more compact and nevertheless able to produce higher sound pressure levels than mobile phones of today. Therefore, loudspeaker designs for mobile phones are pushed in the direction of smaller sizes, more power handling and higher maximum sound pressure capability etc. in order to match the above-mentioned requirements. Also, miniature transducers for handheld devices are under a constant pressure from market demands towards more extreme form factors. Therefore, issues like thermal and acoustical ventilation in miniature loudspeakers or speakers become more and more critical.
The smallest achievable width of prior art miniature transducers is primarily given by the dimensions of an outer magnet and a diaphragm suspension. Thus, if the width of the miniature transducer is to be reduced, the dimensions of the outer magnet and the diaphragm suspension need to be reduced. Another solution could be to omit the outer magnet. However, without the outer magnet the motor of the transducer becomes significantly weaker in strength. In addition, the dimensions of the voice coil also become significantly smaller with thermal problems as a result.
It is an object of the present invention to provide a miniature transducer with reduced dimensions while maintaining the acoustical performance.
It is an advantage of the miniature transducer according to the present invention that it provides, at the same time, a very small width of the transducer, a strong motor and a moving coil with an increased circumference giving optimal thermal conditions.